Through the use of a relatively new and highly sensitive two dimensional immunoelectrophoretic technique we noted a protein in rete testis fluid of vasectomized rats that was not present in control rete testis fluid. This implies that there is a breakdown of the blood-testis barrier at the level of the rete in the vasectomized rats, and is in accord with immunological studies on primates which support the concept of a partial breach of the barrier after vasectomy. Because the response of the monkey's reproductive tract may be similar to that of human, and different from subprimate species, we chose to examine the protein composition in monkey rete testis fluid after vasectomy. In an attempt to identify and characterize the rete testis fluid proteins we will utilize several electrophoretic techniques including two dimensional crossed immunoelectrophoresis, polyacrylamide gel electrophoresis, and standard diffusion immunoelectrophoresis. An important aspect of this work will be to determine whether in normal monkeys there is a blood-epididymal barrier, similar to the blood-testis barrier. Following vasectomy we will examine a number of morphological parameters such as the blood-testis and (blood-epididymal) barrier; penetration of macrophages into the lumina of the excurrent duct system of the testis; integrity of the seminal pathway. The latter portion will include a thorough and exhaustive examination (light and electron microscopy) of all parts of the monkey's reproductive tract after vasectomy. For the barrier studies electron opaque intercellular tracers, such as lanthanum nitrate or horseradish peroxidase, will be utilized to probe the integrity of the junctional complexes, and these data will be correlated with the fine structure of the junctions after thin sectioning and/or freeze cleaving.